Back spasms have put Jeff Gordon's availability into question for Sunday's race at Charlotte Motor Speedway.
The current Sprint Cup points leader missed the majority of Saturday's practice for the Coca-Cola 600, NASCAR's longest race. Gordon ran all of 11 laps before removing himself from the car and leaving the track to seek treatment. The No. 24 team elected not to participate in the afternoon session.
"Unfortunately, I had a back spasm the other night in that last qualifying run that I made," said Gordon, who starts 27th Sunday. "And I've been trying to get it worked out by today, and I got in the car and it just wasn't.
"I just had to tell the team that I think it would be best if I sit out the rest of the day so that I can be prepared for this long, tough race that's going to happen tomorrow."
Hendrick Motorsports will have Regan Smith, the current Nationwide Series points leader, on standby in case Gordon either can't drive or needs relief. Gordon said he expects to start Sunday.
The role of relief driver is not an unfamiliar one for Smith, who drove two races for Dale Earnhardt Jr. when he suffered a concussion in late 2012.
Because Gordon, who won May 10 at Kansas Speedway, qualified his car Thursday, he is not at risk of being ineligible for the Chase for the Sprint Cup if he sits out Sunday.
"It doesn't do me any good to be in the car right now; especially when the car is as good as it is," Gordon said. "It's really about getting prepared for 600 miles tomorrow. I have no doubts that I can be in this car and be competitive tomorrow if I just take it easy over the next 24 hours."
Gordon has not missed a race since making his Cup debut in the 1993 season-finale, a streak of 736 consecutive starts -- the longest among active drivers.